1. Field of the Present Invention
The present invention relates to a novel chondroitin polymerase (chondroitin synthase), a DNA encoding the same, a method for producing the chondroitin polymerase, a method for producing a sugar chain having the disaccharide repeating unit of chondroitin, a hybridization probe for the chondroitin polymerase and the like.
2. Brief Description of the Background Art
First, abbreviations commonly used in the present specification are described.
In the formulae and the like, “GlcUA”, “GalNAc”, “GlcNAc”, “UDP” and “-” represent D-glucuronic acid, N-acetyl-D-galactosamine, N-acetyl-D-glucosamine, uridine 5′-diphosphate and a glycosidic linkage, respectively.
Chondroitin is a sugar chain comprised of a disaccharide repeating structure of GlcUA residue and GalNAc residue (-GlcUAβ(1-3)-GalNAcβ(1-4)-; hereinafter also referred to as “chondroitin backbone”), and a sugar chain in which the chondroitin is further sulfated is chondroitin sulfate.
Regarding an enzyme which synthesizes chondroitin from a GlcUA donor and a GalNAc donor by alternately transferring GlcUA and GalNAc to an acceptor (chondroitin polymerase or chondroitin synthase) and DNA which encodes the same, only a Pasteurella multocida chondroitin synthase (J. Biol. Chem., 275 (31), 24124-24129 (2000)) is known.
Also, certain Escherichia coli strain (Escherichia coli serotype 05:K4 (L):H4, hereinafter referred to as “Escherichia coli strain K4”) produces a polysaccharide having a chondroitin backbone, as a capsular antigen, but its structure is a trisaccharide repeating structure in which fructose is linked to a side chain of the GlcUA residue at the β2-3 position. Accordingly, it was unclear whether the Escherichia coli strain K4 really has a chondroitin polymerase as its own capsular antigen synthesizing system.